Anaerobic digestion and lignocellulosic compositions alteration of industrial vinegar residue after different pretreatments

Abstract

Vinegar residue (VR) is the dominated by-product associated with the industrial process of vinegar brewing. According to statistics, China’ s annual output of VR is around 3.0 million tons, most of which is disposed by landfill or incineration, causing severe resource waste and environment pollution. Anaerobic digestion (AD) may be a promising approach for the stabilization of VR but the complex lignocellulosic structure in VR is a severe challenge for AD performance. To overcome this limitation, a total of 10 different pretreatments were conducted on VR. Alkaline pretreatment was more effective in enhancing the experimental methane yield (EMY) and biodegradability (Bd) in VR, especially 4% alkaline hydrogen peroxide (AHP) pretreatment, showing an increase of 51.7% relative to untreated. The analyses of lignocellulosic compositions alteration, Fourier transform infrared spectra (FTIR), and X-ray diffraction (XRD) revealed that better digestion performance of 4% AHP-treated VR might be attributed to its strong capacity in disrupting the recalcitrant structure of lignocellulose and removing lignin. This study exhibits valuable information relevant to the utilization of VR in future AD applications and presents a reference for the eco-friendly management of other lignocellulosic wastes.